Mongo DB

MongoDB is a source-available cross-platform document-oriented database program.
Classified as a NoSQL database program.
MongoDB uses JSON-like i.e. BSON (Binary Javascript Object Notation) documents with optional schemas
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Developer Docs

Understanding JSON

Start Mongo DB

run mongo command in terminal to start mongoDB

use <database> will create new database, if database does not exist
db.<collection>.insertOne({field: "value1", field2: "value2"}) will insert single document in a database.
show dbs will display all databases present.
show collections will display all collection(set of documents).
db.<collection>.find() will display all the contents of collection

db.<collection>.insertMany({field: "value1"}, {field: "value2"}) will insert multiple documents in a database.
db.<collection>.find({field: "value"}) is used to search in documents
db.<collection>.find({field: "value"}).limit(100) is used to search in collection and display 100 document.
db.<collection>.findOne({field: "value"}) is used to search a single document in a collection.
db.<collection>.updateOne({field: "value"}, {$set: {field: "newValue"}}) is used to update a single document, Here $set:{} is a operator.
db.<collection>.updateMany({field: "value"}, {$set: {field: "newValue"}}) is used to update multiple documents.

db.<collection>.deleteOne({field: "value"}) is used to delete a single document from a collection.

db.<collection>.deleteMany({field: "value"}) is used to delete multiiple documents from a collection.

Creating an CRUD application

To integrate MongoDB with node js, install mongoose module

shell

╰─ npm install mongoose           

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Using mongoose in index.js file to create connection for mongoDB.

javascript

const mongoose = require("mongoose");  
  
mongoose.connect("mongodb://127.0.0.1:27017/TestDB").then(() => {  
		console.log("Connected to MongoDB successfully");  
	}).catch((error) => {  
		console.log(error);  
})

In index.js, here mongoose.Schema() is used to define a schema of the object.

javascript

const user = mongoose.Schema({  
	name: { type: String, required: true },  
	email: { type: String, required: true },  
	age: Number,  
	adult: Boolean,  
});

In index.js , mongoose.model() is used to create a new document.

javascript

const User = mongoose.model("User", user);  
  
const addNewUser = async () => {  
	const newUser = new User({  
		name: "Driptanil",  
		email: "driprecovery@gmail.com",  
		age: 20,  
		adult: false,  
	});  
	await newUser.save();  
};  
  
addNewUser();

javascript

const User = mongoose.model("User", user);  
  
const createNewUser = async () => {  
	const newUser = await User.create({
		name: "Drip",
		email: "drip@drippy.dev",
		age: 20,
		adult: false,
	})  
	console.log("Inserted Succesfully")
};  
  
createNewUser();

Query and Projection Operators

Docs Link